Most helicopter rotors in common use today have long blades which must be removed where compactness is required for storage or transportation of the helicopter. During the early 1920's several patents were granted to Schiesari for propellers and combination propellers and helicopter rotors which incorporated blade member secured by flexible cables to a rotor hub, the blade members further being connected to each other by other flexible cables, thus permitting retraction and extension of the blade members, as shown in U.S. Pat. Nos. 1,478,063, 1,491,972, and 1,517,865. A somewhat similar arrangement is shown in U.S. Pat. No. 2,437,789, granted in 1948. A still more recent patent, granted in 1965, U.S. Pat. No. 3,188,020 shows retractable blades in which spaced apart cables are connected by a membrane which forms an airfoil in flight.
A very interesting patent, not only because of the fame of the inventor, but for a showing of a helicopter rotor in which blade members are supported by flexible cables which form a simple truss-like arrangement, is U.S. Pat. No. 970,616, granted to Thomas A. Edison in 1910. Each blade of the Edison rotor uses a pair of wires or cables secured to front and rear ends of a box kite, the cables converging inwardly from the kite to a winding reel near the center of the rotor hub. Each kite is further provided on its trailing end with a cable declining inwardly to another reel on the hub.